Wow! This was a lot of interesting information. Thank you! But I'm hoping things go well since this is our Bielefelder's first time breeding..........and he already, by some odd and bad chance, tore part of the Leghorn hen's face. Poor baby.I don't know the exact genetics of a Bielefelder, but they are autosexing barred, so I can assume the males are double barred while the females (who show a barring pattern) are single barred like my auto-sexing Cream Legbar.
So you have a double (2 gene) barred rooster, which means 100% of the chicks, both genders will be barred.
Now you have a White Leghorn which usually is dominant white. Her progeny will white out the barring or at best ghost the barring, both genders. Chicks will often be yellow down with a black head spot. Dominant white is really, really hard to get rid of, so that whole line will be affected for generations.
ETA: That hybrid---Leghorn to Bielfelder will be laying machines. You will improve the body size, generally keep the laying capacity, and generally tone down the flightiness of the Leghorn...if you don't mind the "white out" you get color wise.
The red of your Cochin acts as a lovely base to manipulate barring and lacing, depending on the parent side, but you've got a barred male coloring that dominates. Usually you'll then get black and white barred with red leakage both genders and possibly some more red based with black barring as the bielfelder already has red undertones. My hybrid Barnvelder-Cream Legbar males come out very pretty black-white barred with barred red saddles.
You will know your Cochin's progeny as all of it will have foot feathering, nearly 100% first generation in my experience. Cochins are so heavily foot feathered that I have always had hybrid offspring with at least half a boot (outside foot feathering) first gen. Second generation you begin to see the foot feathering drop off, but it will throw back periodically.
The big floppy soft Cochin feathering however seems to drop off with first generation. I have not had soft feathering in any of my Cochin hybrids. Body type also more resembles the layer but is 3/4 size if bred to a Bantam Cochin, which also means 3/4 size eggs. Do you have a standard Cochin? Then body type will likely be heavier than the layer which improves the Bielfelder if you were to go for meat (but I can make assumption that you are more interested in pet/eggs?)
Egg laying tends to be an average of the 2 sides. Bielfelder lays better than the Cochin, so those hybrids will be less than the Bielfelder but a bit better than the Cochin. Standard Cochin adds size and weight for table.
ETA: Save the best rooster from the red-barred cross, and you'll only have a 1 gene barred rooster. Line breed back to your Red Cochin hen, and you can 2nd gen get non-barred 50% both genders, barred 50% both genders. You can then work with the barring side to get back to autosexing 2 barred gene roosters and 1 barred gene females....but only if you are happy with the size and egg capacity of the Cochin line.
He is a very gentle roo, but we believe his size compared to the Leghorn is just too much and makes him clumsier to cause such a mishap. We are actually thinking of giving him away so we don't hurt any other hens if it is the roo thats doing that. Didn't see any blood on the wires since we have all sharp edges tucked away.I would definitely observe them to see what is happening. Mating only takes seconds and shouldn't damage the hen. She may have tore it on a fence or something, but tearing her wattles is not normal mating or interaction. If you have a young roo, he may be over aggressive with mating. A good roo is gentle on the hens though he may grab the back of her neck briefly to stabilize the act.